Crontab.task

#Crontab

Cronjobs are configured in crontab files. Do not edit these files directly. Use crontab -e instead. This runs all required actions to activate a cronjob after saving the edited crontab. The locations are as follows:

/var/spool/cron/username user specific
/etc/crontab system wide crontab
The format of the files is (user specific crontabs do not have the column user-name):

Example of job definition:
.---------------- minute (0 - 59 | */5 [every 5 minutes])
|  .------------- hour (0 - 23)
|  |  .---------- day of month (1 - 31)
|  |  |  .------- month (1 - 12) OR jan,feb,mar,apr ...
|  |  |  |  .---- day of week (0 - 6) (Sunday=0 or 7) OR sun,mon,tue,wed,thu,fri,sat
|  |  |  |  |
*  *  *  *  * user-name  command to be executed
Command	Description
rpm -q cronie	Check if package is installed
systemctl status crond.service	Check if service is running
crontab -l	List current users crontab
crontab -e	Edit current users crontab
crontab -e -u username	Edit specific users crontab
crontab -r	Remove current users crontab
Script folders

Scripts in one of the following directories will be executed at the intervall specified by the directory's name:

/etc/cron.hourly
/etc/cron.daily
/etc/cron.weekly
/etc/cron.monthly
Allow / Deny usage

Add user names one per line to the following files:

/etc/cron.allow Whitelist
/etc/cron.deny Blacklist
If none of the files exists, all users are allowed.

Logs and Results

Execution of cronjobs is logged in /var/log/cron. Results are sent to the users mail /var/spool/mail/username